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<br />the pit slopes at all times at a 2:1 or 1.5:1 slope while leaving some rock in place to minimize <br />chance of the Colorado River capturing the pit during a high flow event and causing a slope <br />failure. An alternative would be for the operator to maintain the excavations in a "dry" condition <br />until such time that all backfilling and grading to desired reclamation contours is completed. <br />Please address. <br />4. The applicant needs to commit to locating topsoil stockpiles out of floodway of the Colorado <br />River and preferably on the uphill side of the excavations. Exhibit C -Pre-mining & Mining <br />Plan Maps will need to be revised to verify that all product, overburden, and topsoil stockpiles <br />will be located out of the floodway of the Colorado River. Please address. <br />5. The applicant has proposed a series of barriers to protect the property lines, Colorado River <br />and associated riparian areas, Dry Creek, Mamm Creek and the slough area. The barriers appear <br />to be based on arbitrary distances ranging from 50 to 150 feet. The Division is in favor of <br />barriers, although the barrier design and location should be based on the elevation difference <br />between the top of the proposed barrier and the active channel of the Colorado River during <br />mining and reclamation, rather than an arbitrary distance. Ultimately, the applicant will need to <br />demonstrate that such barriers aze designed and will be located is such a way to provide <br />protection against a 25-year flood event of the Colorado River, both in terms of flood elevation <br />and flow velocity for such an event. Cross sectional designs for each barrier including size of <br />material in each barrier will be needed as well as a revised copy of Exhibit C to show the location <br />of such barriers. (The Division may be willing to consider a design and location of barriers for a <br />10-yeaz flood event, although the applicant will need to provide a reclamation bond adequate to <br />cover the cost of reestablishing such berms in the unlikely event of a significant flood event and <br />corresponding slope failure). Please address. <br />6. The applicant has proposed that in addition to the in pit crushing and screening equipment, •a <br />variety of facilities (concrete batch plant, asphalt plant, sand & gravel stockpiles, etc.) will likely <br />be installed during the life of the operation. Please verify whether there will be one (1) main <br />processing and stockpile area or whether there will be several or more. (If the applicant proposes <br />to have several or more processing and stockpile areas, the applicant will need to provide the <br />location of such facilities on a revised copy of Exhibit C. As mentioned in Item 4 above, the <br />applicant will need to verify that al] such facilities are located outside the floodway of the <br />Colorado River). <br />7. In order to evaluate the potential for offsite impacts during mining, the applicant will need to <br />describe the location of any nearby alluvial gravel mining operations (either upstream or <br />downstream), how far upstream or downstream they will be from the Marton Creek excavations, <br />and the nature of the other operations, ie: are they located within or outside of the active channel <br />of the Colorado River. Also, the applicant will need to describe the location and elevation of any <br />significant water features within the affected land or surrounding area such as the water intake <br />structure and recharge zone for [he City of Rifle. If possible, the location of such structures <br />should be noted on a revised copy of the Mining Plan Map, Exhibit C. Please address. <br />8. The applicant indicates that the "Renewable Resource Area" (RRA) will be located in an <br />